import numpy as np
import pandas as pd

arr = np.random.randint(1,20,size=(3,3))
df = pd.DataFrame(arr,columns=['c','b','a'])

print('原始数据：\n',df)
print('按行索引降序排序：\n',df.sort_index(ascending=False))
print('按行索引升序排序：\n',df.sort_index(axis=1))